A variety of drug delivery devices are known in the art. These include implants, various polymers, microcapsules, liposomes, stents and many hybrids devices. While these drug delivery devices work well in certain body locations, such as skin or muscle tissue, they often fail to work in moist tissue locations. In moist tissue, such as mucosal membranes or tissue in the serous cavities, there is a problem keeping the drug delivery device in place for a sufficiently long time to provide the requisite delivery of the drug at the proper site. While physical methods of keeping the drug delivery device at the proper site, such as the use of sutures have been tried, there may still be problems with controlling the delivery rate or biocompatibility. Accordingly, it has been theorized that an adherent drug delivery device might provide certain benefits.
Various bioadhesives are known in the art. U.S. Pat. No. 4,615,697, issued to Robinson et al., defines a bioadhesive as a material that requires a force of at least about 50 dynes/cm2 to separate two adhered, freshly excised pieces of rabbit stomach, following the procedure disclosed therein. The bioadhesive disclosed in Robinson et al. is a water-swellable, but water insoluble, fibrous, cross-linked carboxy-functional polymer.
The bioadhesives described in the Robinson patent actually show cohesive failure rather than adhesive failure (see Example 1 above). In contrast, the use of NOCC as the bioadhesive in the drug delivery device allows one to tailor the device such that failure of breakaway from tissue can be controlled to be either adhesive or cohesive as desired. In addition, biocompatibility is improved where desired. These devices can also be tailored to provide sustained release of drugs in a controlled manner. In addition, Robinson""s polymers are not bioresorbable.
Accordingly, it is an object of the invention to provide new adherent devices and methods of drug delivery to moist tissue.
Another object of the invention is to provide adherent drug delivery devices for use with moist tissue that can be tailored in terms of delivery time and compatibility through the use of additional structural materials.
A further object of the invention is to provide an adherent drug delivery device and methods of their use for buccal, eye, vaginal, gastrointestinal, or intra-serous cavity drug delivery.
A still further object of the invention is to provide an adherent coating that helps prevent the formation of surgical adhesions.
An additional object of the invention is to provide an adherent coating that helps seal tissue.
These and other objects and features of the invention will be apparent from the detailed description and the claims.
The present invention features a method of utilizing an adherent form of N,O-carboxymethylchitosan (xe2x80x9cNOCCxe2x80x9d) to deliver a series of materials to tissue. The invention is based, in part, on the discovery of adherent coatings of NOCC may be applied to various substrates, such as mammalian tissue, so as to allow delivery of materials such as drugs or hormones to the specific site.
The present invention provides a series of compositions that is adherent to a variety of synthetic materials and mammalian tissues. These compositions can be used as a device for vaginal delivery of hormones, as buccal implants, as eye implants or drug delivery devices and the like for localized or systemic delivery of a variety of materials when adhered to the delivery site.
In one embodiment, the invention provides a composition and method of delivering drugs, proteins, and other therapeutic agents from an adhesive device or composition that is adherent to soft (mucosal or non-mucosal) tissue or hard tissue. In preferred embodiments, the adherent delivery device can be used as a buccal, oral, vaginal, inhalant, or the like delivery system. The device can be in a variety of forms including solutions, creams, pellets, particles, beads, gels, and pastes. In some embodiments, the NOCC is supplemented with a structural support material selected from the group consisting of rubber, plastic, resin, natural and synthetic polymers, and mixtures thereof.
The method is useful for providing sustained release of a drug to moist tissue. The method uses the steps of applying to said moist tissue a drug delivery device which is adherent to said moist tissue and includes a level of N,O-carboxymethylchitosan as a component thereof to provide said adherence. The drug delivery device further containing a sufficient quantity of the drug to be delivered to provide sustained release of said drug and permeation into said moist tissue. The preferred moist tissues are mucosal tissue and tissue within serous cavities. Preferred mucosal tissue is tissue of the oral cavity such as buccal tissue, vaginal tissue, ocular tissue, and gastrointestinal tissue. Preferred tissues within a serous cavity are tissues within the pleural, pericardial or peritoneal cavities.
The method is useful for delivering a number of drugs such as chlorhexidine, tetracycline and mixtures thereof for treatment of buccal problems like mouth sores and periodontal disease or drugs such as melatonin and chlorpheniramine through the buccal mucosa for systemic therapy. The method can also be used to deliver drugs to the vaginal tissue like progestins, estrogens, antifungal agents, antibacterial agents, anti-viral agents, proteins and peptides, particularly levonorgestrel. Similarly, the method can be used to deliver drugs to ocular tissue such as beta blockers and glaucoma treating drugs.
The method of the invention may also provide for adherence or sealing of tissue and prevention of post-surgical adhesions. This method utilizes a medical device that includes NOCC and optionally, a tissue sealant such as a fibrin sealant or a cyanoacrylate. In this case, the preferred moist tissue is at the site of a surgical incision. The primary tissues to be sealed are lung tissues, heart tissues and intestinal tissue.